Leptophis mystacinus
- 演化之聲
- Mar 12
- 4 min read
Updated: Apr 10
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Squamata
Family: Colubridae
Genus: Leptophis
Species: Leptophis mystacinus
Morphological description
The whiskered parrot snake Leptophis mystacinus is a slender, laterally compressed diurnal colubrid. Its overall appearance is typical of arboreal snakes: the body is cylindrical with a slightly flattened ventral surface, and the paraventral region forms a distinct angle. The head is elongated and clearly differentiated from the neck. The snout is extended, the eyes are large, and the pupils are round.
One of the most characteristic traits of this species is the dorsal color pattern. Along the dorsolateral region runs a bright green longitudinal stripe, while the dorsal scales immediately below this stripe usually display a deep yellow tone. Behind the eye lies a highly conspicuous black postocular stripe that extends posteriorly toward the neck and may reach as far as approximately 11 scales in length, noticeably longer than in most closely related species. Anterior to the eye, the black stripe is reduced to a narrow margin along the edges of the supralabial scales and the upper margin of the rostral scale. The ventral surface is generally white to smoky white. Juveniles, as well as some adult females, may retain dark transverse bands on the anterior to midbody region, a pattern commonly seen in juvenile individuals of many species within the genus Leptophis.
The holotype specimen (ZUFMS-REP004702) is an adult female with a snout–vent length of approximately 47.5 cm and a tail length of about 32.3 cm. The largest recorded male specimen (ZUFMS-REP004703) has a snout–vent length of approximately 73.8 cm and a tail length of about 50 cm.
Etymology
The genus name Leptophis derives from the Greek words leptos, meaning “slender,” and ophis, meaning “snake,” together referring to a “slender snake.”
The species name mystacinus originates from the Greek mystax (μύσταξ), meaning “upper lip” or “mustache,” combined with the Latin suffix -inus, indicating possession of a particular feature or resemblance. The name directly refers to the distinctive black stripe pattern on the head of this species, which in many individuals creates the visual impression of a mustache extending along the upper lip.
Biological description
Leptophis mystacinus is a snake distributed in central to southeastern Brazil. Its currently confirmed range includes the states of Tocantins and Minas Gerais. Based on the known specimen localities, the species occurs primarily within the Cerrado biome, but its distribution also extends into transitional areas influenced by the Amazon rainforest, such as the northern Tocantins localities of Araguaína, Caseara, and Pium. This distribution pattern suggests that the species is not strictly confined to a single vegetation type but can occur within ecological mosaics where Cerrado savanna and adjacent humid forests meet.
From a biogeographic perspective, the whiskered parrot snake belongs to the South American dry diagonal biota. This broad belt stretches across several major ecosystems—including the Caatinga, the Cerrado, and the Chaco—which differ in climate and vegetation structure yet share numerous closely related evolutionary lineages. Leptophis mystacinus appears to represent the Cerrado lineage within this pattern, whereas its closest sister species, Leptophis dibernardoi, occurs primarily in the Caatinga and along adjacent regions of the Atlantic Forest margin. Such sister-species distributions across neighboring ecological regions are consistent with evolutionary patterns observed in many other reptile groups within the South American dry diagonal.
Evidence from reproductive biology further indicates that the species is oviparous. At least one dissected female specimen (CHUNB 52572) contained four well-developed eggs, the first measuring approximately 3.1 cm along the head-to-tail axis. This record confirms that Leptophis mystacinus lays eggs and that reproductive activity occurs within the Cerrado ecosystem where the specimen was collected.
Some individuals of this species—particularly larger females or specimens with incomplete tails—retain dark transverse bands along the anterior and middle portions of the body. In most Leptophis species such banding is characteristic of juveniles, but in Leptophis mystacinus the pattern may persist into adulthood in certain individuals. This indicates that the ontogenetic color transition varies among individuals and does not disappear uniformly with increasing body size or with sex.
From a systematic and evolutionary perspective, molecular analyses indicate that Leptophis mystacinus forms a strongly supported monophyletic lineage based on mitochondrial 16S DNA sequences. Phylogenetically, it is the sister species of Leptophis dibernardoi, with an average genetic divergence of approximately 2%.
The discovery of Leptophis mystacinus highlights once again that the Brazilian Cerrado still harbors snake diversity that remains incompletely documented. Because species of Leptophis are morphologically very similar, reliance solely on quantitative traits such as scale counts often fails to reliably distinguish species. As a result, some specimens from Tocantins were previously tentatively assigned to other species. The recognition of Leptophis mystacinus indicates that the region's snake diversity and biogeographic history remain subjects requiring further investigation.
（Author: Shui-Ye You）
Reference
Albuquerque NR et al. (2025). A new species of parrot snake, Leptophis (Serpentes: Colubridae) from the Brazilian Cerrado. PeerJ.
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